PROJECT SUMMARY - Comparative Effectiveness Core A growing number of advanced imaging technologies, such as digital breast tomosynthesis and breast magnetic resonance imaging (MRI), are being used for breast cancer screening and surveillance. However, the evidence base for understanding their best use, and comparing the impact of different breast imaging strategies on population mortality, is lacking. The Breast Cancer Surveillance Consortium (BCSC) has unique data and an established infrastructure to document breast cancer screening and surveillance performance among women in diverse community settings. Dartmouth College, a BCSC site, has extensive resources and expertise in decision-analytic modeling and economic evaluation, including an established collaboration with the NCI-funded Cancer Intervention and Surveillance modeling Network (CISNET). Futhermore, Dartmouth researchers have been pioneers in the study of cancer screening, risk communication, and overdiagnosis. The Comparative Effectiveness (CE) Core, based at Dartmouth College, will provide specialized expertise in decision science, risk communication, survey research, economic evaluation, and simulation modeling to efficiently support the program's comparative effectiveness and translational goals. In this competing renewal, the CE Core will expand its services to support identification of clinically-actionable risk-based screening and surveillance strategies, in collaboration with Projects 1 and 3. This will be accomplished through surveys and Delphi panels with key stakeholders including women and healthcare providers. Working with three CISNET breast cancer modeling groups, the CE Core will continue to provide comparative modeling services that will translate short-term project results to a longer time horizon, addressing the net benefits, harms, and costs of innovative breast cancer screening strategies tailored based on risk of screening outcome in collaboration with Projects 1 and 2. The CE Core specific aims are to 1) provide essential methodological expertise in decision sciences, risk communication, and survey research and model resources to support all program-related comparative effectiveness and clinical translational goals; 2) support identification of clinically-actionable ranges of unacceptable risk for poor screening and surveillance outcomes; 3) support evaluation of the long- term comparative effectiveness for innovative screening strategies defined using clinically-actionable ranges of unacceptable risk for poor screening outcomes to determine screening interval and/or modality. Centralization of survey research, modeling and other specialized services within the CE Core will enhance interactions across all program components. Research supported by the CE Core will provide information on the most effective and efficient risk-based breast cancer screening strategies. Furthermore, CE Core supported findings will inform future risk communication to support tailored screening and surveillance and will facilitate future dissemination and implementation studies focused on overcoming barriers to risk-based imaging.